Mechanical Muscle Function, Morphology, and Fiber Type in Lifelong Trained Elderly

AAGAARD, PER1; MAGNUSSON, PETER S.2; LARSSON, BENNY3; KJÆR, MICHAEL2; KRUSTRUP, PETER4

Medicine & Science in Sports & Exercise:
doi: 10.1249/mss.0b013e31814fb402
BASIC SCIENCES: Original Investigations
Abstract

Purpose: Maximal muscle contraction force and muscle mass are both reduced during the natural aging process. Long-term training may be used to attenuate this age-related loss in muscle function and muscle size.

Methods: Maximum isometric quadriceps strength (MVC), rate of force development (RFD), and muscle fiber composition and size (CSA) were studied in elderly individuals (68-78 yr) chronically exposed (> 50 yr) to either endurance (E) or strength (S) training, and in age-matched, untrained (U) elderly group.

Results: E and S showed greater MVC than did U. Contractile RFD was elevated in S compared with U, and S also demonstrated greater type II fiber CSA than did U and E. The proportion of type I fibers was greater in E compared with U and S.

Conclusions: Muscle fiber size and mechanical muscle performance, particularly RFD, were consistently elevated in aged individuals exposed to chronic (i.e., lifelong) strength training. This relative preservation in muscle morphology and function may provide an important physical reserve capacity to retain muscle mass and function above the critical threshold for independent living at old age.

Author Information

1Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, DENMARK; 2Institute of Sports Medicine Copenhagen, Copenhagen, DENMARK; 3Team Danmark Testcentre, Bispebjerg Hospital, University of Copenhagen, Copenhagen, DENMARK; and 4Institute of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, DENMARK

Address for correspondence: Per Aagaard, Ph.D., Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, DK-5230, Odense, Denmark; E-mail: paagaard@health.sdu.dk.

Submitted for publication January 2007.

Accepted for publication July 2007.

©2007The American College of Sports Medicine